Phylogenetics and phylogeographic characteristics of coxsackievirus A16 in hand foot and mouth disease and herpangina cases collected in Beijing, China from 2019 to 2021.

Coxsackievirus A16 (CV-A16) is a significant pathogen responsible for causing hand foot and mouth disease (HFMD) and herpangina (HA). This study aimed to investigate the recent evolution and spread of CV-A16 by monitoring HFMD and HA cases in 29 hospitals across 16 districts in Beijing from 2019 to 2021. The first five cases of HFMD and the first five cases of HA each month in each hospital were included in the study. Real-time reverse transcription polymerase chain reaction was used to identify CV-A16, CV-A6, and EV-A71. From each district, two to four CV-A16 positive samples with a relatively long sampling time interval every month were selected for sequencing. A total of 3344 HFMD cases and 2704 HA cases were enrolled in this study, with 76.0% (2541/3344) of HFMD and 45.4% (1227/2704) of HA cases confirmed to be infected by enterovirus. Among the EV-positive samples, CV-A16 virus was detected in 33.61% (854/2541) of HFMD cases and 13.4% (165/1227) of HA cases, with the predominant cluster being B1a. Both B1a and B1b had a co-circulation of local and imported strains, with different origin time (1993 vs. 1995), different global distribution (14 countries vs. 10 countries), and different transmission centers but mainly distributed in the southern and eastern regions of Beijing. Strengthening surveillance of HFMD in southern and eastern regions will improve the prevention and control efficiency of enterovirus infections.

Molecular epidemiology and phylodynamic analysis of enterovirus 71 in Beijing, China, 2009-2019.

BACKGROUND: Enterovirus 71(EV71)-associated hand, foot and mouth disease (HFMD) decreased dramatically in Beijing from 2009 to 2019. This study was to investigate the epidemiological characteristics, evolutionary dynamics, geographic diffusion pathway, and other features of EV71 in Beijing, China. METHODS: We conducted a retrospective study of EV71-associated HFMD and its causative agent in Beijing, China, from 2009 to 2019. Phylogenetic and phylogeographic methods based on the EV71 genome were used to determine the evolution features, origin, and spatiotemporal dynamics. Positive selection sites in the VP1 gene were identified and exhibited in the tertiary structure. Bayesian birth-death skyline model was used to estimate the effective reproductive number (Re). RESULTS: EV71-associated HFMD decreased greatly in Beijing. From 2009 to 2019, EV71 strains prevalent in Beijing shared high homology in each gene segment and evolved with a rate of 4.99*10- 3 substitutions per site per year. The genetic diversity of EV71 first increased and peaked in 2012 and then decreased with fluctuations. The time to the most recent common ancestor (TMRCA) of EV71 in Beijing was estimated around 2003 when the EV71 strains were transmitted to Beijing from east China. Beijing played a crucial role in seeding EV71 to central China as well. Two residues (E145Q/G, A293S) under positive selection were detected from both the VP1 dataset and the P1 dataset. They were embedded within the loop of the VP1 capsid and were exposed externally. Mean Re estimate of EV71 in Beijing was about 1.007. CONCLUSION: In recent years, EV71 was not the primary causative agent of HFMD in Beijing. The low Re estimate of EV71 in Beijing implied that strategies for preventing and controlling HFMD were performed effectively. Beijing and east China played a crucial role in disseminating EV71 to other regions in China.

A Dendritic Cells-Targeting Nano-Vaccine by Coupling Polylactic-Co-Glycolic Acid-Encapsulated Allergen with Mannan Induces Regulatory T Cells.

BACKGROUND: The efficacy of allergen-specific immunotherapy (AIT) is mainly depended on the tolerogenic immune responses elicited. Properly conjugated nano-vaccine has the advantages of both specific targeting and continuous and on-demand release of allergen. OBJECTIVES: The aim of this study is to investigate the effects of a dendritic cells (DCs)-targeting nano-vaccine for AIT. METHODS: The nano-vaccine was produced by coupling polylactic-co-glycolic acid (PLGA)-encapsulated ovalbumin (OVA) with mannan. Allergen capture, human monocytes-derived DCs (hMoDCs) activation, and T cells responses were assessed by flow cytometry, confocal microscopy, quantitative real-time PCR, ELISA, and Cytometric Bead Array. Balb/c mice were immunized with the nano-vaccines, and the immune responses were analyzed. RESULTS: OVA-PLGA nanoparticle (NP) displayed favorable safety profile. OVA-mannan-PLGA NP was captured more efficiently by hMoDCs than OVA-PLGA NP, which was mediated mainly through DC-specific intercellular adhesion molecule 3-grabbing nonintegrin. A tolerogenic phenotype of hMoDCs was induced by OVA-mannan-PLGA NP, but not OVA-PLGA NP, and increased number of regulatory T (Treg) cells was generated subsequently in in vitro coculture. Immunization of Balb/c mice with OVA-mannan-PLGA NP resulted in lower serum level of OVA-specific immunoglobulins and less production of pro-inflammatory cytokines in splenocytes culture than the mice immunized with OVA-PLAG NP, PLGA NP, or OVA, while the number of splenic Treg cells was higher in OVA-mannan-PLGA group than in other groups. Moreover, preimmunization with OVA-mannan-PLGA NP significantly inhibited the Th2 immune response induced by OVA sensitization. CONCLUSIONS: The biocompatible PLGA-encapsulated OVA coupling with mannan has augmented ability for tolerance induction and could be developed as a novel vaccine for AIT.

Encapsulation of a Phase-Change Material in Nanocapsules with a Well-Defined Hole in the Wall for the Controlled Release of Drugs.

As a class of biocompatible and biodegradable phase-change materials, natural fatty acids have received considerable interest in recent years for temperature-controlled release of drugs. However, the poor dispersibility and colloidal stability of their nanoparticles under physiological conditions place a major limitation on their applications in biomedicine. Herein, we report a facile method for encapsulating a mixture of two natural fatty acids (with a eutectic melting point at 39 °C) in a biocompatible, silica-based nanocapsule to achieve both stable dispersion and controllable release of drugs. The nanocapsules have a well-defined hole in the wall to ensure easy loading of fatty acids, together with multiple types of functional components such as therapeutics and near-infrared dyes. The payloads can be released through the hole when the fatty acids are melted upon photothermal heating. The release profile can be controlled by varying the size of the hole and/or the duration of laser irradiation.

An outbreak of Coxsackievirus A6-associated hand, foot, and mouth disease in a kindergarten in Beijing in 2015.

BACKGROUND: Coxsackievirus A6 (CVA6) is one of the major agents to cause hand, foot and mouth disease (HFMD) outbreaks globally. The objective of this study is to investigate the epidemiologic and clinical manifestations of CVA6 outbreak, and thus guide the diagnosis and treatment of the disease, as well as disease prevention. METHODS: An HFMD outbreak in a kindergarten was reported to Shijingshan District Center for Disease Control and Prevention (SCDC) on November 2, 2015 in Beijing, China. Epidemiological investigation was conducted. We performed a nine-week follow-up study to collect and analyze the clinical manifestations of HFMD cases. RESULTS: The outbreak yield 56 (15.7%) clinical diagnosed HFMD cases out of 357 registered children in the kindergarten with the mean age of 3.5 years old. This outbreak lasted for three days and ceased after initiating infectious disease controlling procedures, including periodical suspension of the kindergarten activities, environmental disinfection, and family health education. Fifty-one cases were followed for nine weeks. The positive rate of clinical manifestations of rash, fever, desquamation, pigmentation and onychomadesis were 100.0%, 84.3%, 68.6%, 17.6% and 43.1%, respectively. Children developed desquamation within the first 4 weeks after disease onset and developed onychomadesis between the 3th and 8th week after disease onset. Children with desquamation had 9.3 (95%CI: 1.836-47.437) times higher odds of developing onychomadesis compared to those without this manifestation. Ten out of 14 collected samples were CVA6 positive, and five positive samples shared a high degree of similarity in the VP1 nucleotide and amino acid sequences (99.9-100.0% and 100%). CONCLUSION: This HFMD outbreak was caused by CVA6, featured with delayed symptoms. Emerging CVA6-associated HFMD and its delayed symptoms should be paid more attention to reduce outbreaks and provide more information to doctors and parents.

Detecting spatial-temporal cluster of hand foot and mouth disease in Beijing, China, 2009-2014.

BACKGROUND: The incidence of hand, foot, and mouth disease (HFMD) is extremely high, and has constituted a huge disease burden throughout Beijing in recent years. This study aimed to determine the spatiotemporal distribution and epidemic characteristics of HFMD. METHODS: Descriptive statistics was used to analyze the data and estimate the epidemic peaks in 2009-2014. Space-time scanning detected spatiotemporal clusters and identified high-risk locations. Global and local Moran's I statistics were used to measure the spatial autocorrelation. Geocoding was performed in ArcGIS, based on the present address codes of the patients and the centroids of the towns. Maps were created in ArcGIS to show the geographic spread of HFMD. RESULTS: In total, 220,451probable cases of HFMD were reported in Beijing between January 2009 and December 2014: 12,749 (5.78 %) were laboratory confirmed, and 35 (0.02 %) were fatal. The median age of reported cases was 3.12 years (interquartile range 1.96-4.39). Coxsackievirus A16 (CV-A16), enterovirus 71 (EV-A71), and other enteroviruses accounted for 39.31, 35.36, and 25.33 % of the 12,749 confirmed cases, respectively. Many more severe cases were caused by EV-A71 (χ (2) = 186.41, df = 1, P < 0.001) and other enteroviruses (χ (2) = 156.44, df = 1, P < 0.001) than by CV-A16. A large single distinct peak occurred between May and July each year. Spatiotemporal clusters of HFMD were identified in Beijing during 2009-2014. The most likely clusters were detected and tended to move from the southwest (Fengtai and Daxing) southeastwards to Daxing and Tongzhou in 2009-2014. The incidence of HFMD was not randomly distributed, but showed global and local spatial autocorrelations. CONCLUSIONS: There were obvious spatiotemporal clusters of HFMD in Beijing in 2009-2014. High-incidence areas mainly occurred at the junctions of urban and rural zones. More attention should be paid to the epidemiological and spatiotemporal characteristics of HFMD to establish new strategies for its control. Health issues should be especially promoted in kindergartens and at urban-rural junctions.

Economic Burden of Hand, Foot, and Mouth Disease - Beijing Municipality, China, 2016-2019.

What is already known about this topic?: Current research regarding hand, foot, and mouth disease (HFMD) has primarily concentrated on the economic impacts, drawing from retrospective or sentinel hospital-based data. This approach often overlooks cases that were either not consulted or were misdiagnosed. What is added by this report?: This research systematically examined the iceberg phenomenon of HFMD and its economic implications in Beijing. Our findings indicate that each confirmed case represents 9.1 actual infections, imposing financial burdens of 25.58 United States dollars (USD) per unconsulted individual, 265.75 USD per misdiagnosed individual, 366.50 USD per individual with mild cases, and 2355.89 USD per individual with severe cases. The annual economic losses attributed to HFMD in the area range from 7.03 million USD to 13.31 million USD. What are the implications for public health practice?: This study offers insight into the actual prevalence of HFMD in Beijing, as well as conducting an economic burden analysis on a per-case, per-category basis. This could facilitate a cost-effectiveness analysis of prevention and control strategies for HFMD.

Mechanism underlying the toxicity of the microplastic fibre transfer in the sea cucumber Apostichopus japonicus.

Microscopic plastic particles (0.1 µm-5 mm) are widespread hazardous pollutants, and microfibres (MFs) are their dominant shape in habitats. Previous field and laboratory studies have demonstrated that MFs enter the coelomic fluid of sea cucumbers from the water through the respiratory tree. However, the possible mechanism underlying the toxicity of this process is not well understood. Herein, RNA-Seq was used to examine the responses of the respiratory tree during the MF transfer process in the sea cucumber Apostichopus japonicus. Polyester synthetic MFs were used, and the number of transferred MFs was controlled to the amount reported from the field. The results showed that the MFs altered gene expression as the transfer process increased. The top genes regulated by MF transfer were mainly related to metabolic processes and signal transduction pathways, with upregulated genes following low MF transfer and downregulated genes following high MF transfer. Functional enrichment analysis revealed the pathways in which differentially expressed genes were enriched under different MF transfer scenarios. The transcriptomic findings were further supported by histological observations, which revealed injury and loss of cell components. This study contributes to understanding the effects of MFs in a valuable echinoderm species through transcriptomic and histological examinations.

Enterovirus A71 vaccine effectiveness in preventing enterovirus A71 infection among medically-attended hand, foot, and mouth disease cases, Beijing, China.

INTRODUCTION: Enterovirus A71(EV-A71)-associated hand, foot, and mouth disease (HFMD) has been reported worldwide, and poses a particularly heavy burden on patients, families, and society in China. Three Chinese companies have licensed inactivated EV-A71 vaccines, all of which have demonstrated good efficacy for preventing EV-A71-associated disease in clinical trials. However, real-world performance of EV-A71 vaccine has not been evaluated. METHODS: We used a test-negative design case-control study to estimate vaccine effectiveness (VE) against medically attended EV-A71-associated HFMD. Subjects were children 5 years of age and under who had been in health facilities participating in the HFMD case and virologic surveillance platforms in Beijing. Enterovirus infections were laboratory confirmed, and EV-A71 vaccination status was extracted from electronic immunization records. Children testing positive for EV-A71 were cases; controls were children testing negative for EV-A71 infection. Logistic regression was used to estimate VE. We assessed sensitivity of VE estimates to control group inclusion criteria by repeating the regression analyses with two alternative control groups. RESULTS: A total of 2,184 HFMD patients aged 5 years and under were enrolled in the study; 24 were severe, and 2,160 were mild. For severe cases, two-dose VE estimate was 100% (95% CI: -68.1%, 100%). For mild cases, 1-dose and 2-dose adjusted VE estimates were 69.8% and 83.7%, respectively. Two-dose VE estimates varied by less than 4 percentage points regardless of control group definition. CONCLUSIONS: Our findings suggested the vaccines performed well in the real world for children 5 years of age and under in Beijing, China.

Continuous processing of phase-change materials into uniform nanoparticles for near-infrared-triggered drug release.

We report a method based on interfacial, anti-solvent-induced precipitation in a fluidic device for the continuous and scalable processing of phase-change materials (PCMs) into uniform nanoparticles with controlled diameters in the range of 10-100 nm. A eutectic mixture of lauric acid and stearic acid, with a well-defined melting point at 39 °C, serves as an example to demonstrate the concept. In the fluidic device, a coaxial flow is created by introducing a PCM solution in ethanol and a lipid solution in water (the anti-solvent) as the focused and focusing phases, respectively. The formation of lipid-capped PCM nanoparticles is governed by diffusion-controlled mixing of ethanol and water. During the production, both doxorubicin (DOX, an anticancer drug) and indocyanine green (ICG, a near-infrared dye) can be readily loaded into the PCM nanoparticles to give a smart drug release system. Upon irradiation with near-infrared light, the photothermal heating caused by ICG can melt the PCM and thereby trigger the release of DOX. This work not only provides a new technique for the continuous processing of PCMs and other soft materials into uniform nanoparticles with controlled sizes but also demonstrates a biocompatible system for controlled release and related applications.

Analysis of an Imported Subgenotype C2 Strain of Human Enterovirus 71 in Beijing, China, 2015.

Background: Subgenotype C4 of enterovirus 71 (EV71) is the predominant agent of Hand Foot and Mouth disease (HFMD) circulating in the mainland of China. For the first time, a subgenotype C2 of EV71 named SY30-2 was isolated from a HFMD case in Beijing, China. Since it is uncertain whether antibodies raised against subgenotype C4 of EV71 can protect C2 EV71, it is important to monitor and check the presence of cross-reactive antibodies against new EV71 subgenotypes. To find out the causes for the different NtAb, this study is to investigate the relationships between amino acid residue variations and cross-reactive antibodies against EV71 subgenotypes C2 and C4. Methods: Nucleotide and amino acid sequences from full-length genome sequence of SY30-2 were compared to EV71 reference strains. A microneutralization test was used to detect neutralizing antibody (NTAb) in the sera of subgenotype C4 of EV71 infected cases against SY30-2 and FY17 (a C4 isolate). The 3D structure of the viral capsid protein of SY30-2 was constructed. Results: Genome sequence and similarity plot analyses showed that SY30-2 shared the highest identity with subgenotype C2 of EV71 strains in every fragment of the genome. While the microneutralization test result showed that children infected with subgenotype C4 of EV71 had higher NTAb titers against FY17 than SY30-2 (p < 0.001). The amino acid sequence comparison revealed that four amino acid residues VP1-22, VP1-31, VP1-249 and VP3-93 were highly conserved in subgenotype C4 of EV71 compared with the corresponding amino acid residues on subgenotype C2 of EV71 (p < 0.05). Furthermore, the 3D-structure of viral capsid protein showed that VP1-22, VP1-31 and VP3-93 were located on the surface of virion. Conclusion: This is the first report of an EV71 subgenotype C2 isolated from HFMD in Beijing, China. Only a few antigenic variations on subgenotype C2 of EV71 could have led to a great decrease in NTAb titer. Thus, imported new genotypes and subgenotypes of EV71 should be closely monitored. The efficacy of available vaccines against new viruses should be evaluated as well.

Antishear Stress Bionic Carbon Nanotube Mesh Coating with Intracellular Controlled Drug Delivery Constructing Small-Diameter Tissue-Engineered Vascular Grafts.

Small-diameter (<6 mm) tissue-engineered blood vessels (TEBVs) have a low patency rate due to chronic inflammation mediated intimal hyperplasia. Functional coating with drug release is a promising solution, but preventing the released drug from being rushed away by blood flow remains a great challenge. A single-walled carboxylic acid functionalized carbon nanotube (C-SWCNT) is used to build an irregular mesh for TEBV coating. However, an interaction between the released drug and the cells is still insufficient due to the blood flow. Thus, an intracellular drug delivery system mediated by macrophage cellular uptake is designed. Resveratrol (RSV) modified CNT is used for macrophage uptake. M1 macrophage uptakes CNT-RSV and then converts to the M2 phenotype upon intracellular RSV release. Prohealing M2 macrophage inhibits the chronic inflammation thus maintains the contractile phenotype of the vascular smooth muscle cell (VSMC), which reduces intimal hyperplasia. Additionally, RSV released from the mesh coating also directly protects the contractile VSMCs from being converted to a secretory phenotype. Through antishear stress coating and macrophage-based intracellular drug delivery, CNT-RSV TEBVs exhibit a long-term anti-intimal hyperplasia function. Animal transplantation studies show that the patency rate remains high until day 90 after grafting in rat carotid arteries.

Micropatterned Polymer Nanorod Forests and Their Use for Dual Drug Loading and Regulation of Cell Adhesion.

This paper describes a simple method for the fabrication of micropatterned polymer nanorod forests by templating against the channels in an anodized aluminum oxide membrane partially masked by gelatin. The nanorod forests easily support bimodal drug loading, with one drug encapsulated in the nanorods and the other physisorbed on their surface. During cell culture, preosteoblasts are predominantly attracted to the nanorod forests and driven to climb up along the nanorods. This type of scaffold integrates both microscale and nanoscale features into a single substrate, holding great potential for applications in cell culture and tissue engineering.

Characterization of Coxsackievirus A6- and Enterovirus 71-Associated Hand Foot and Mouth Disease in Beijing, China, from 2013 to 2015.

BACKGROUND: Etiology surveillance of Hand Foot and Mouth disease (HFMD) in Beijing showed that Coxsackievirus A6 (CVA6) became the major pathogen of HFMD in 2013 and 2015. In order to understand the epidemiological characteristics and clinical manifestations of CVA6-associated HFMD, a comparison study among CVA6-, EV71- (Enterovirus 71), and CVA16- (Coxsackievirus A16) associated HFMD was performed. METHODS: Epidemiological characteristics and clinical manifestations among CVA6-, EV71- and CVA16-associated mild or severe cases were compared from 2013 to 2015. VP1 gene of CVA6 and EV71 from mild cases, severe cases were sequenced, aligned, and compared with strains from 2009 to 2015 in Beijing and strains available in GenBank. Phylogenetic tree was constructed by neighbor-joining method. RESULTS: CVA6 became the predominant causative agent of HFMD and accounted for 35.4 and 36.9% of total positive cases in 2013 and 2015, respectively. From 2013 to 2015, a total of 305 severe cases and 7 fatal cases were reported. CVA6 and EV71 were responsible for 57.5% of the severe cases. Five out six samples from fatal cases were identified as EV71. High fever, onychomadesis, and decrustation were the typical symptoms of CVA6-associated mild HFMD. CVA6-associated severe cases were characterized by high fever with shorter duration and twitch compared with EV71-associated severe cases which were characterized by poor mental condition, abnormal pupil, and vomiting. Poor mental condition, lung wet rales, abnormal pupil, and tachycardia were the most common clinical features of fatal cases. The percentage of lymphocyte in CVA6-associated cases was significantly lower than that of EV71. High percentage of lymphocyte and low percentage of neutrophils were the typical characteristics of fatal cases. VP1 sequences between CVA6- or EV71-associated mild and severe cases were highly homologous. CONCLUSION: CVA6 became one of the major pathogens of HFMD in 2013 and 2015 in Beijing. Epidemiological characteristics, clinical manifestations of CVA6-, EV71- and CVA16-associated cases in this study enriched the definition of HFMD caused by different pathogens and shed light to accurate diagnosis, appropriate treatment and effective prevention of HFMD.

Fabrication of Au@Ag core-shell NPs as enhanced CT contrast agents with broad antibacterial properties.

Au@Ag core-shell nanoparticles (NPs) integrating both antibacterial and X-ray attenuation capabilities were facilely synthesized in aqueous solution. These NPs modified with methoxy-PEG-SH (m-PEG) on the surface rendered them favorable dispersity and stability in water, resulting in enhancement of their blood circulation time. X-ray photoelectron spectroscope (XPS) and high-resolution transmission electron microscope (HRTEM) results confirmed the core-shell structure of m-PEG-Au@Ag NPs. The m-PEG-Au@Ag NPs showed low cytotoxicity and strong X-ray absorption potency in vitro. Further in vivo study showed that as-synthesized NPs offered a pronounced contrast and prolonged their circulation time in the blood stream with negligible toxic effect in vivo. Besides, m-PEG-Au@Ag NPs had significant bacteriostatic effect toward common bacteria like Escherichia coli and Staphylococcus aureus as demonstrated by broth dilution assay. Given their low-cytotoxicity and high CT attenuation efficacy, m-PEG-Au@Ag NPs had a promising potential for use as CT enhancing and antibacterial agents.

Facile synthesis of polymer core@silver shell hybrid nanoparticles with super surface enhanced Raman scattering capability.

Silver nano-shells (SNSs) were synthesized via a two-step seeds-mediated method. Polymer cores were composed of ultrafine gold nanoparticles (NPs) modified chitosan-poly(acrylic acid) nanoparticles (CS-PAA NPs). Then, deposition of silver upon gold nucleus leads to the seed enlargement and finally forms silver shell on the surface of CS-PAA NPs to get SNSs. Transmission electron microscope (TEM) showed SNSs had a discrete silver shell plus some pores and gaps, which could acted as "hot spots" and provided the great potential of these SNSs to be used as SERS substrates with wavelength ranging from visible to infrared region (700-1000 nm) by tuning shell coverage of silver. SERS experiments with dibenzyl disulphide (DBDS) as the indicator showed that the resulting SNSs allowed the production of highly consistent enhancement of the Raman signals down to nM concentrations of DBDS. Considering the excellent biocompatibility of polymer core and their small size, these SNSs are highly desirable candidates as the enhancers for high performance SERS analysis and as SERS optical labels in biomedical imaging.

Synthesis of ß-cyclodextrin modified chitosan-poly(acrylic acid) nanoparticles and use as drug carriers.

ß-Cyclodextrin modified chitosan-poly(acrylic acid) nanoparticles (CS-PAACD NPs) were obtained by polymerizing acrylic acid (AA) and ß-cyclodextrin (ß-CD) substituted acrylic acid (AACD) in chitosan (CS) solution. These CS-PAACD NPs, characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) as well as atomic force microscopy (AFM), were quite small in size about 40-50 nm. The size and the microstructure of these CS-PAACD NPs could be accurately controlled by changing the ration of AACD to AA. As the ratio of AACD to AA increased, the size of these NPs decreased. These as-prepared CS-PAACD NPs showed enhanced solubility for paclitaxel (PTX) in aqueous solution and exhibited a typical pH-sensitive release property for the encapsulated drug in vitro. The presence of the ß-cyclodextrin inside the CS-PACD NPs greatly enhanced the ability to load hydrophobic drugs, which significantly broadened the application of CS-PAACD NPs in biomedical fields.

In situ formation of chitosan-gold hybrid hydrogel and its application for drug delivery.

A novel chitosan-gold (CS-Au) hybrid hydrogel was developed from chitosan and chloroauric acid in aqueous solution. Its physiochemical characteristics, including UV absorption, structure, morphology, swelling properties were studied. The CS-Au hybrid hydrogel exhibited an excellent water-absorbing property and could be applied as a drug delivery system for anticancer drug: doxorubicin (DOX) due to its high equilibrium water swelling content. The drug loading and release experiments elicited an efficient drug loading content and sustained drug release pattern. Moreover, DOX released from hydrogel which itself had no cytotoxicity was biological active similar as the free DOX, but lower cytotoxicity due to its controllable release. All proved it an ideal local drug delivery system indicating a promising potential future in medical or pharmaceutical area.